* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: sans-serif;
}

ul li {
  list-style: none;
}

body {
  display: grid;
  place-items: center;
  height: 100vh;
  background-color: #232c33;
}

nav {
  position: relative;
  width: 60px;
  height: 500px;
  background-color: #2b343b;
  box-shadow: 10px 0 0 #4187f6;
  overflow: hidden;
  transition: width 0.5s;
  display: grid;
  place-items: center;
}
nav ul {
  position: relative;
  z-index: 1;
  width: 100%;
  margin-left: 10px;
}
nav ul li {
  position: relative;
  cursor: pointer;
  height: 60px;
  color: #fff;
  white-space: nowrap;
  border-top-left-radius: 20px;
  border-bottom-left-radius: 20px;
}
nav ul li span {
  display: inline-block;
  text-align: center;
  pointer-events: none;
}
nav ul li .icon {
  line-height: 60px;
  min-width: 60px;
  font-size: 1.5rem;
  vertical-align: middle;
}
nav ul li .title {
  line-height: 60px;
  white-space: nowrap;
}
nav:hover {
  width: 300px;
}
nav .slider {
  z-index: 0;
  transition: all cubic-bezier(0.075, 0.82, 0.165, 1) 500ms;
  border-top-left-radius: 20px;
  border-bottom-left-radius: 20px;
  height: 60px;
  width: 100%;
  position: absolute;
  background-color: #4187f6;
}
nav .slider::after {
  content: "";
  position: absolute;
  top: -30px;
  right: 0;
  height: 30px;
  width: 30px;
  box-shadow: 15px 15px 0 #4187f6;
  border-radius: 50%;
}
nav .slider::before {
  content: "";
  position: absolute;
  bottom: -30px;
  right: 0;
  height: 30px;
  width: 30px;
  box-shadow: 15px -15px 0 #4187f6;
  border-radius: 50%;
}